US20080034884A1 - Piezoceramic-based smart aggregate for unified performance monitoring of concrete structures - Google Patents

Piezoceramic-based smart aggregate for unified performance monitoring of concrete structures Download PDF

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US20080034884A1
US20080034884A1 US11/825,370 US82537007A US2008034884A1 US 20080034884 A1 US20080034884 A1 US 20080034884A1 US 82537007 A US82537007 A US 82537007A US 2008034884 A1 US2008034884 A1 US 2008034884A1
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concrete
piezoceramic
pzt
transducers
transducer
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US7987728B2 (en
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Gangbing Song
Haichang Gu
Yi-Lung Mo
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University of Houston System
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University of Houston System
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0066—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by exciting or detecting vibration or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0033—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining damage, crack or wear

Definitions

  • This invention is related to the field of monitoring devices and, more specifically, to the field of performance monitoring of concrete structures.
  • the current maturity meter measures the hydration heat of a concrete structure and the hydration time at early-age to estimate the strength development of a concrete structure.
  • An ultrasonic velocity meter evaluates some physical properties of a concrete structure by measuring the velocity of ultrasonic waves propagated inside the concrete structure.
  • Compressive test equipment determines the compressive strength data of concrete by directly compressing and crushing the concrete specimens (structure) but, due to the press method, equipment and other uncertain factors, large amounts of concrete specimens are needed for the test which is time-consuming and effort consuming.
  • the present technological methods to evaluate the strength of concrete at early-age can be classified into two categories: (1) destructive method that crushes the concrete for strength testing and (2) non-destructive testing.
  • Hydration heat-based method evaluates the early-age strength development of concrete by measuring the hydration heat and recording the hydration time. This kind of method cannot be applied to the health monitoring of concrete structure after the concrete strength is fully developed.
  • the ultrasonic velocity-based method applies an ultrasonic meter on the surface of concrete structure to measure the velocity of the ultrasonic waves from the surface to evaluate the concrete strength.
  • the shortcoming of this method is that the variation of the wave velocity of the ultrasonic waves is not sensitive to the strength of the concrete. A ten percent increment of strength may only result in less than one percent increment of the wave velocity.
  • the invention is a novel unified performance-monitoring device (based on piezoelectricity) for concrete structures.
  • a smart aggregate is directly embedded into a concrete structure at the desired location before casting and can be used, not only for early-age strength monitoring of concrete, but also for the health monitoring (crack and damage detection and evaluation) of concrete structure after the concrete strength has been fully developed.
  • This invention reduces the maintenance cost and effort of civil concrete structures and is also capable of giving precaution warnings before the failure of concrete structures.
  • This invention has the advantages of low cost, unified evaluation of concrete from early-age through the life-time, and easy implementation.
  • FIG. 1 is a perspective illustration of the piezoceramic transducer with waterproof coating.
  • FIG. 2 is an exploded view of smart aggregates embedded in a concrete structure.
  • FIG. 3 illustrates the experimental setup for strength testing and health monitoring testing.
  • FIG. 5 is a chart illustrating the crack width measured by microscope and LVDT.
  • FIG. 6 is a chart showing the damage index curve vs. load of PZT 2 .
  • FIG. 7 is a chart showing the damage index curve vs. load of PZT 3 .
  • FIG. 8 is a chart showing the damage index curve vs. load of PZT 4 .
  • FIG. 9 is a photograph of a test frame setup with the reinforced concrete bent-cap specimen.
  • FIG. 10 is a perspective view of the present invention showing the location of smart aggregates.
  • FIG. 11 is a chart showing the crack width measured by microscope (MS) and LVDT.
  • FIG. 12 is a chart of the time response of PZT 10 with PZT 3 as actuator excited by the sweep sine (100-10k Hz).
  • FIG. 13 is a chart of the damage index vs. load for PZT 1 with PZT 3 as actuator.
  • FIG. 15 is a chart of the damage index vs. load for PZT 5 with PZT 3 as actuator.
  • FIG. 16 is a chart of the damage index vs. load for PZT 8 with PZT 3 as actuator.
  • FIG. 17 is a chart of the damage index vs. load for PZT 9 with PZT 3 as actuator.
  • FIG. 18 is a chart of the damage index vs. load for PZT 10 with PZT 3 as actuator.
  • FIG. 21 is a chart showing the compressive strength of the concrete vs. age.
  • FIG. 22 is a chart showing the amplitude of specimens I, II and III for 60k harmonic response.
  • FIG. 23 is a chart showing the amplitude of specimens I, II and III for 100k harmonic response.
  • FIG. 24 is a chart showing the average value of the amplitude of different harmonic excitation.
  • FIG. 25 is a chart of the average value of the amplitude of different harmonic excitation after the seventh day.
  • FIG. 27 is a chart of the membership function of the output variable (compressive strength).
  • FIG. 28 is a chart showing the experimental training data and the fuzzy mapping data.
  • FIG. 29 is a chart showing the experimental compressive strength and the estimated compressive strength.
  • FIG. 30 is a chart of the experimental data for healthy monitoring of concrete cylinder specimen.
  • the present invention is a piezoceramic-based smart aggregate 100 (see FIG. 1 ) for unified performance monitoring of concrete structures 102 and the method of making the smart aggregate 100 .
  • a piezoceramic transducer 104 is formed from a piezoceramic patch 106 with electric wires 108 and a waterproof, insulating coating 110 .
  • One preferred embodiment of the smart aggregate 100 contains an 8 mm ⁇ 8 mm ⁇ 0.267 mm piezoceramic patch 106 , the waterproof insulating coating 110 , two soldered electric wires 108 on two sides of the piezoelectric patch 106 that are all embedded in a small cubic concrete block 112 .
  • This is meant by way of example and is not intended to limit the scope of the invention.
  • This smart aggregate 100 of the present invention has three obvious advantages over the current technology for early-age concrete performance evaluation:
  • the smart aggregate 100 can be applied to the evaluation of concrete performance from the beginning of the hydration period through the life-time maintenance period.
  • Other current, early-age concrete evaluation devices cannot be applied for the health monitoring (crack detection and evaluation) during the maintenance period.
  • the present invention 100 is suitable for the performance evaluation of the in-situ, large-scale concrete structures 102 which may be inaccessible for other current devices (not shown) to evaluate the early-age concrete performance.
  • the present invention 100 is very economical. The cost of one invented device 100 is approximately one dollar which is much less than the current transducer (not shown) for early-age concrete performance evaluation.
  • FIG. 2 shows the smart aggregate 100 embedded in the concrete structure 102 .
  • FIG. 3 is a preferred embodiment of an experimental testing system 120 for strength testing and health monitoring testing.
  • the system 120 includes two smart aggregates (embedded in a concrete cylinder specimen 306 ) that are attached to industry standard devices (such as a function generator 300 , a power amplifier 302 , and an oscilloscope 304 ) via the electric wires 108 .
  • the smart aggregate 100 can be used as either an actuator 100 a or sensor 100 s as depicted in FIG. 2 .
  • the function generator 300 and the power amplifier 302 generate a signal to the smart aggregate 100 a to induce a mechanical force (shown in FIG. 2 ).
  • the mechanical force is detected by the smart aggregate 100 s and the smart aggregate 100 s provides a signal to the oscillator 304 .
  • the mechanical This test setup is meant by way of example and is not meant to limit the scope of the invention.
  • the patch 106 is coated with waterproof coating layers 110 as shown in FIG. 1 .
  • the smart aggregate 100 as shown in FIG. 2 , is manufactured by embedding the coated, piezoelectric patch 106 into a small, cubic concrete block 112 .
  • the smart aggregate 100 is then positioned at a pre-determined place in the concrete structure 102 before casting, as shown in FIG. 2 .
  • This invention 100 is then used to conduct early-age strength monitoring and health monitoring after the concrete strength is fully developed.
  • the present invention uses a novel treatment of the piezoceramic transducer 104 .
  • the piezoceramic transducer can be constructed from various ceramic materials, such as lead (plumbum) zirconate titanate (PZT).
  • PZT lead (plumbum) zirconate titanate
  • the piezoceramic transducer 104 is first coated with water-proof insulating layers 110 and then embedded into a cubic concrete block 112 to form the smart aggregate 100 .
  • the smart piezoceramic-based aggregates 100 are then directly embedded into the concrete structure 102 to evaluate the performance of the concrete in the structure 102 .
  • Concrete cylinders with smart aggregates were tested.
  • the strength monitoring experimental data verified the effectiveness of the invention to monitor the strength development of concrete at early ages.
  • the health monitoring experimental data verified the effectiveness of the invention to be applied to the health monitoring of the concrete structure.
  • FIG. 4 shows one test of four smart aggregates 100 embedded into a concrete bent-cap concrete structure 102 .
  • FIG. 5 is a chart of the test results (measured by microscope and LVDT) showing Crack Width vs Load V.
  • FIGS. 6-8 are charts showing the results of the Damage Index vs. Load for actuator PZT 1 and sensors PZT 2 , PZT 3 and PZT 4 , respectively.
  • FIG. 9 is a photograph of a test frame setup with the reinforced concrete bent-cap specimen 102 and four hydraulic actuators (A-D).
  • FIG. 10 is a view of the test frame setup showing the location of the smart aggregates (PZT 1 -PZT 10 ) 100 .
  • FIG. 11 is a chart of the crack width measured by microscope and LVDT.
  • FIG. 12 is a graph of the sensor voltage vs. time showing the time response of PZT 10 with PZT 3 as actuator excited by the sweep sine (100-10k Hz).
  • FIGS. 13-18 are graphs showing the Damage Index vs. load for PZT 1 , PZT 2 , PZT 5 , PZT 8 , PZT 9 and PZT 10 , respectively, with PZT 3 as the actuator (sweep sine 10-100 Hz).
  • FIG. 19 is a photograph of an experimental setup for early-age strength monitoring of concrete specimens using an Agilent Function Generator, a Quickpack Power Amplifier, a Multifrequency LCR meter, a LeCroy Digital Oscilloscope and three concrete cylinder specimens.
  • FIG. 20 is a photograph of a Universal compression testing machine for concrete cylinder compressive strength testing.
  • FIG. 21 is a graph showing the compressive strength vs age (days) for the testing done on the Universal compression testing machine.
  • FIGS. 22-23 are graphs showing the amplitudes of specimens 308 a, b, c (see FIG. 19 ) for 60 k and 100k harmonic response, respectively.
  • FIGS. 24-25 are graphs showing the average values of the amplitude of different harmonic excitation for various days.
  • FIGS. 26-27 are graphs showing the membership function of input (harmonic amplitude) and output (compressive strength) variables, respectively.
  • FIG. 28 is a graph showing the experimental training data and the fuzzy mapping data and FIG. 29 shows the experimental compressive strength and the estimated compressive strength.
  • FIG. 30 is a graph of the experimental data for health monitoring of concrete cylinder specimen (sensor voltage vs. time).
  • FIG. 31 shows the Damage Index data for the concrete cylinder specimen.

Abstract

A system for monitoring the health of a structure, e.g., a concrete wall, bridge, pillars, using a smart aggregate is disclosed. The smart aggregate includes a piezoceramic transducer(s) and associated communication links. The transducer is embedded into the structure prior to the manufacture of the structure. The disclosed system can monitor internal stresses, cracks and other physical forces in the structures during the structures' life. The system is capable of providing an early indication of the health of the structure before a failure of the structure can occur.

Description

    CROSS-REFERENCE TO RELATED APPLICATION
  • This application claims benefits from U.S. provisional application Ser. No. 60/819,202 filed Jul. 7, 2006, the entire contents of which are hereby incorporated herein by reference.
    • FIELD OF THE INVENTION
  • This invention is related to the field of monitoring devices and, more specifically, to the field of performance monitoring of concrete structures.
    • BACKGROUND OF THE INVENTION
  • Current early-age concrete evaluation devices, such as the maturity meter, cannot be applied for the detection and evaluation of cracks and damage for the maintenance period. Some other early-age concrete evaluation devices, such as ultrasonic wave velocity meters, require bulky equipment and are not suitable for the health monitoring of in-situ, large-scale concrete structures.
  • The current maturity meter measures the hydration heat of a concrete structure and the hydration time at early-age to estimate the strength development of a concrete structure. An ultrasonic velocity meter evaluates some physical properties of a concrete structure by measuring the velocity of ultrasonic waves propagated inside the concrete structure.
  • Compressive test equipment determines the compressive strength data of concrete by directly compressing and crushing the concrete specimens (structure) but, due to the press method, equipment and other uncertain factors, large amounts of concrete specimens are needed for the test which is time-consuming and effort consuming.
  • The present technological methods to evaluate the strength of concrete at early-age can be classified into two categories: (1) destructive method that crushes the concrete for strength testing and (2) non-destructive testing.
  • Two popular non-destructive methods to evaluate the early-age strength development of concrete are the hydration heat-based method and the ultrasonic wave velocity-based method. Hydration heat-based method evaluates the early-age strength development of concrete by measuring the hydration heat and recording the hydration time. This kind of method cannot be applied to the health monitoring of concrete structure after the concrete strength is fully developed.
  • The ultrasonic velocity-based method applies an ultrasonic meter on the surface of concrete structure to measure the velocity of the ultrasonic waves from the surface to evaluate the concrete strength. The shortcoming of this method is that the variation of the wave velocity of the ultrasonic waves is not sensitive to the strength of the concrete. A ten percent increment of strength may only result in less than one percent increment of the wave velocity.
  • Early-age concrete performance is an important and critical issue for the construction of the concrete structures. The construction speed and the quality evaluation of concrete at an early-age are the major concerns for the construction of civil concrete structures. After the concrete is cured, the detection of the existence and growth of cracks and damage is another important issue for the maintenance of civil concrete structures.
  • It is an object of the present invention, therefore, to extend the lifetime of concrete structures. It is a further object of the invention to enhance the safety of concrete buildings. It is also an object of the present invention to reduce the maintenance effort and cost for concrete structures.
    • BRIEF SUMMARY OF THE INVENTION
  • The invention is a novel unified performance-monitoring device (based on piezoelectricity) for concrete structures. A smart aggregate is directly embedded into a concrete structure at the desired location before casting and can be used, not only for early-age strength monitoring of concrete, but also for the health monitoring (crack and damage detection and evaluation) of concrete structure after the concrete strength has been fully developed.
  • This invention reduces the maintenance cost and effort of civil concrete structures and is also capable of giving precaution warnings before the failure of concrete structures.
  • This invention has the advantages of low cost, unified evaluation of concrete from early-age through the life-time, and easy implementation.
  • This invention has the potential to be manufactured in large quantities of commercial product as a meter for early-age performance evaluation and health monitoring (crack detection and evaluation) for civil concrete structures. The commercial product, based on this invention, will have a very competitive price and offer promising profits for civil construction companies, civil maintenance companies and related industrial companies.
  • The commercial market for the invented device is an obvious promising one due to the reason that the invented device is a great necessity for the early-age performance evaluation, the health monitoring during the maintenance period of large-scale concrete structures, such as bridges, buildings, and pillars. The safety and the life-time of the concrete structure are greatly improved by using the invented device.
    • BRIEF DESCRIPTION OF THE FIGURES
  • FIG. 1 is a perspective illustration of the piezoceramic transducer with waterproof coating.
  • FIG. 2 is an exploded view of smart aggregates embedded in a concrete structure.
  • FIG. 3 illustrates the experimental setup for strength testing and health monitoring testing.
  • FIG. 4 shows a concrete bent-cap (structure) with four smart aggregates embedded.
  • FIG. 5 is a chart illustrating the crack width measured by microscope and LVDT.
  • FIG. 6 is a chart showing the damage index curve vs. load of PZT2.
  • FIG. 7 is a chart showing the damage index curve vs. load of PZT3.
  • FIG. 8 is a chart showing the damage index curve vs. load of PZT4.
  • FIG. 9 is a photograph of a test frame setup with the reinforced concrete bent-cap specimen.
  • FIG. 10 is a perspective view of the present invention showing the location of smart aggregates.
  • FIG. 11 is a chart showing the crack width measured by microscope (MS) and LVDT.
  • FIG. 12 is a chart of the time response of PZT10 with PZT3 as actuator excited by the sweep sine (100-10k Hz).
  • FIG. 13 is a chart of the damage index vs. load for PZT1 with PZT3 as actuator.
  • FIG. 14 is a chart of the damage index vs. load for PZT2 with PZT3 as actuator.
  • FIG. 15 is a chart of the damage index vs. load for PZT5 with PZT3 as actuator.
  • FIG. 16 is a chart of the damage index vs. load for PZT8 with PZT3 as actuator.
  • FIG. 17 is a chart of the damage index vs. load for PZT9 with PZT3 as actuator.
  • FIG. 18 is a chart of the damage index vs. load for PZT10 with PZT3 as actuator.
  • FIG. 19 is a photograph of an experimental setup for early-age strength monitoring of concrete specimens.
  • FIG. 20 is a photograph of a Universal compression testing machine for concrete cylinder compressive testing.
  • FIG. 21 is a chart showing the compressive strength of the concrete vs. age.
  • FIG. 22 is a chart showing the amplitude of specimens I, II and III for 60k harmonic response.
  • FIG. 23 is a chart showing the amplitude of specimens I, II and III for 100k harmonic response.
  • FIG. 24 is a chart showing the average value of the amplitude of different harmonic excitation.
  • FIG. 25 is a chart of the average value of the amplitude of different harmonic excitation after the seventh day.
  • FIG. 26 is a chart of the membership function of the input variable (harmonic amplitude).
  • FIG. 27 is a chart of the membership function of the output variable (compressive strength).
  • FIG. 28 is a chart showing the experimental training data and the fuzzy mapping data.
  • FIG. 29 is a chart showing the experimental compressive strength and the estimated compressive strength.
  • FIG. 30 is a chart of the experimental data for healthy monitoring of concrete cylinder specimen.
  • FIG. 31 is a chart of the damage index data for concrete cylinder specimen.
    • DETAILED DESCRIPTION OF THE INVENTION
  • The present invention is a piezoceramic-based smart aggregate 100 (see FIG. 1) for unified performance monitoring of concrete structures 102 and the method of making the smart aggregate 100. A piezoceramic transducer 104 is formed from a piezoceramic patch 106 with electric wires 108 and a waterproof, insulating coating 110.
  • One preferred embodiment of the smart aggregate 100, as shown in FIG. 1, contains an 8 mm×8 mm×0.267 mm piezoceramic patch 106, the waterproof insulating coating 110, two soldered electric wires 108 on two sides of the piezoelectric patch 106 that are all embedded in a small cubic concrete block 112. This is meant by way of example and is not intended to limit the scope of the invention.
  • This smart aggregate 100 of the present invention has three obvious advantages over the current technology for early-age concrete performance evaluation:
  • (1) The smart aggregate 100 can be applied to the evaluation of concrete performance from the beginning of the hydration period through the life-time maintenance period. Other current, early-age concrete evaluation devices cannot be applied for the health monitoring (crack detection and evaluation) during the maintenance period.
  • (2) The present invention 100 is suitable for the performance evaluation of the in-situ, large-scale concrete structures 102 which may be inaccessible for other current devices (not shown) to evaluate the early-age concrete performance.
  • (3) The present invention 100 is very economical. The cost of one invented device 100 is approximately one dollar which is much less than the current transducer (not shown) for early-age concrete performance evaluation.
  • FIG. 2 shows the smart aggregate 100 embedded in the concrete structure 102.
  • FIG. 3 is a preferred embodiment of an experimental testing system 120 for strength testing and health monitoring testing. The system 120 includes two smart aggregates (embedded in a concrete cylinder specimen 306) that are attached to industry standard devices (such as a function generator 300, a power amplifier 302, and an oscilloscope 304) via the electric wires 108. The smart aggregate 100 can be used as either an actuator 100 a or sensor 100 s as depicted in FIG. 2. The function generator 300 and the power amplifier 302 generate a signal to the smart aggregate 100 a to induce a mechanical force (shown in FIG. 2). The mechanical force is detected by the smart aggregate 100 s and the smart aggregate 100 s provides a signal to the oscillator 304. The mechanical This test setup is meant by way of example and is not meant to limit the scope of the invention.
  • Method of Creating
  • To protect the piezoelectric patch 106 from water and moisture, the patch 106 is coated with waterproof coating layers 110 as shown in FIG. 1. The smart aggregate 100, as shown in FIG. 2, is manufactured by embedding the coated, piezoelectric patch 106 into a small, cubic concrete block 112. The smart aggregate 100 is then positioned at a pre-determined place in the concrete structure 102 before casting, as shown in FIG. 2. This invention 100 is then used to conduct early-age strength monitoring and health monitoring after the concrete strength is fully developed.
  • The present invention uses a novel treatment of the piezoceramic transducer 104. The piezoceramic transducer can be constructed from various ceramic materials, such as lead (plumbum) zirconate titanate (PZT). The piezoceramic transducer 104 is first coated with water-proof insulating layers 110 and then embedded into a cubic concrete block 112 to form the smart aggregate 100. The smart piezoceramic-based aggregates 100 are then directly embedded into the concrete structure 102 to evaluate the performance of the concrete in the structure 102.
  • Test Results for the Invention
  • Concrete cylinders with smart aggregates were tested. The strength monitoring experimental data verified the effectiveness of the invention to monitor the strength development of concrete at early ages. The health monitoring experimental data verified the effectiveness of the invention to be applied to the health monitoring of the concrete structure.
  • The following figures show the results of the testing which are an impressive improvement over current methods:
  • FIG. 4 shows one test of four smart aggregates 100 embedded into a concrete bent-cap concrete structure 102. FIG. 5 is a chart of the test results (measured by microscope and LVDT) showing Crack Width vs Load V.
  • FIGS. 6-8 are charts showing the results of the Damage Index vs. Load for actuator PZT1 and sensors PZT2, PZT3 and PZT4, respectively.
  • FIG. 9 is a photograph of a test frame setup with the reinforced concrete bent-cap specimen 102 and four hydraulic actuators (A-D).
  • FIG. 10 is a view of the test frame setup showing the location of the smart aggregates (PZT1-PZT10) 100.
  • FIG. 11 is a chart of the crack width measured by microscope and LVDT.
  • FIG. 12 is a graph of the sensor voltage vs. time showing the time response of PZT10 with PZT3 as actuator excited by the sweep sine (100-10k Hz).
  • FIGS. 13-18 are graphs showing the Damage Index vs. load for PZT1, PZT2, PZT5, PZT8, PZT9 and PZT10, respectively, with PZT3 as the actuator (sweep sine 10-100 Hz).
  • FIG. 19 is a photograph of an experimental setup for early-age strength monitoring of concrete specimens using an Agilent Function Generator, a Quickpack Power Amplifier, a Multifrequency LCR meter, a LeCroy Digital Oscilloscope and three concrete cylinder specimens.
  • FIG. 20 is a photograph of a Universal compression testing machine for concrete cylinder compressive strength testing.
  • FIG. 21 is a graph showing the compressive strength vs age (days) for the testing done on the Universal compression testing machine.
  • FIGS. 22-23 are graphs showing the amplitudes of specimens 308 a, b, c (see FIG. 19) for 60 k and 100k harmonic response, respectively.
  • FIGS. 24-25 are graphs showing the average values of the amplitude of different harmonic excitation for various days.
  • FIGS. 26-27 are graphs showing the membership function of input (harmonic amplitude) and output (compressive strength) variables, respectively.
  • FIG. 28 is a graph showing the experimental training data and the fuzzy mapping data and FIG. 29 shows the experimental compressive strength and the estimated compressive strength.
  • FIG. 30 is a graph of the experimental data for health monitoring of concrete cylinder specimen (sensor voltage vs. time).
  • FIG. 31 shows the Damage Index data for the concrete cylinder specimen.
  • The above described embodiments are intended to be illustrative only and in no way limiting. The described embodiments of carrying out the invention are susceptible to many modifications of form, arrangement of parts, details and order of operation. The invention, rather, is intended to encompass all such modification within its scope, as defined by the claims.

Claims (15)

1. A system for monitoring the health of a structure, comprising:
a plurality of piezoceramic transducers coated with an insulating material whereby the piezoceramic transducers are embedded in the structure;
a generator coupled to a first piezoceramic transducer; and
a monitor coupled to a second piezoceramic transducer whereby the monitor displays a waveform received by the second piezoceramic transducer that was generated by the first piezoceramic transducer.
2. The system of claim 1 wherein the piezoceramic transducers are lead zirconate titanate transducers.
3. The system of claim 1 wherein the structure is composed of concrete.
4. The system of claim 3 wherein the structure is a bridge.
5. The system of claim 3 wherein the structure is a building.
6. The system of claim 3 wherein the structure is a pillar.
7. The system of claim 1 wherein the insulating material is composed of water-proof insulating layers.
8. The system of claim 3 wherein the piezoceramic transducers include a piezoceramic material with a volume no greater than 8 mm×8 mm×0.267 mm.
9. The system of claim 3 wherein the piezoceramic transducers are embedded in a concrete block whereby the concrete block is embedded in the structure.
10. A method for monitoring the health of a structure, comprising the steps of:
coating piezoceramic transducers with an insulating material;
embedding the piezoceramic transducers into a housing;
embedding the housing into the structure;
inducing a first waveform from a first piezoceramic transducer; and
displaying a second waveform received by a second piezoceramic transducer.
11. The method of claim 10 wherein the structure is composed of concrete.
12. The method of claim 11 wherein the step of embedding the housing occurs prior to the curing of the concrete.
13. The method of claim 12 wherein the piezoceramic transducers are composed of lead zirconate titanate.
14. The method of claim 13 wherein the housing is a cubic concrete block.
15. The method of claim 14 wherein the insulating material is composed of water-proof insulating layers.
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CN104285131A (en) * 2012-05-25 2015-01-14 意法半导体股份有限公司 A package, made of building material, for a parameter monitoring device, within a solid structure, and relative device
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US9500247B2 (en) 2010-11-01 2016-11-22 University Of Houston Pounding tune mass damper with viscoelastic material
CN106770653A (en) * 2016-12-05 2017-05-31 大连理工大学 It is a kind of to stack formula piezoelectric intelligent aggregate for concrete structure health monitoring
CN106948488A (en) * 2017-05-05 2017-07-14 长沙理工大学 Preparation method, combination beam and the monitoring device of compound transfer structure for SRC beams
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CN107275474A (en) * 2017-05-04 2017-10-20 浙江大学 A kind of piezoelectricity girder test specimen and preparation method thereof and test method
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CN113552220A (en) * 2021-08-13 2021-10-26 同济大学 Reinforced concrete structure health monitoring system
EP3933356A1 (en) 2020-07-01 2022-01-05 Université Libre de Bruxelles Piezoelectric ultrasonic transducer embedded in concrete structures
CN117349601A (en) * 2023-12-06 2024-01-05 济南大学 Concrete damage classification method and system based on piezoelectric vibration waves

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102401707B (en) * 2011-08-30 2013-08-14 湖南大学 Dynamic concrete stress sensor and calibrating method based on piezoelectric ceramics
KR101257304B1 (en) * 2011-10-17 2013-04-23 한국건설기술연구원 Ultrasonic test apparatus for determining concrete strength and slip form method for constructing concrete structure using ultrasonic test apparatus
US9836801B2 (en) 2012-01-23 2017-12-05 Quipip, Llc Systems, methods and apparatus for providing comparative statistical information in a graphical format for a plurality of markets using a closed-loop production management system
US9254583B2 (en) 2012-01-23 2016-02-09 Quipip, Llc Systems, methods and apparatus for providing comparative statistical information for a plurality of production facilities in a closed-loop production management system
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US10677765B2 (en) 2017-12-12 2020-06-09 Honeywell International Inc. Structural health monitoring of cyclically loaded structures

Citations (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4480480A (en) * 1981-05-18 1984-11-06 Scott Science & Technology, Inc. System for assessing the integrity of structural systems
US4849668A (en) * 1987-05-19 1989-07-18 Massachusetts Institute Of Technology Embedded piezoelectric structure and control
US5421204A (en) * 1993-06-08 1995-06-06 Svaty, Jr.; Karl J. Structural monitoring system
US5520055A (en) * 1993-11-13 1996-05-28 Dornier Gmbh Apparatus for monitoring the fatigue strength of structures
US6069433A (en) * 1994-01-27 2000-05-30 Active Control Experts, Inc. Packaged strain actuator
US6076405A (en) * 1994-08-31 2000-06-20 Honeywell International Inc. Remote self-powered structure monitor
US6240783B1 (en) * 1998-05-02 2001-06-05 Usbi, Co Bridge monitoring system
US20040078170A1 (en) * 2002-10-17 2004-04-22 Don Di Marzio System and method for monitoring a structure
US6781285B1 (en) * 1994-01-27 2004-08-24 Cymer, Inc. Packaged strain actuator
US20040200613A1 (en) * 2003-04-08 2004-10-14 Fripp Michael L. Flexible piezoelectric for downhole sensing, actuation and health monitoring
US20050061076A1 (en) * 2003-09-22 2005-03-24 Hyeung-Yun Kim Sensors and systems for structural health monitoring
US6928881B2 (en) * 2000-06-29 2005-08-16 University College London Method and apparatus for monitoring structural fatigue and use
US7065846B2 (en) * 2002-07-11 2006-06-27 Ceramtec Ag Innovative Ceramic Engineering Insulation for piezoceramic multilayer actuators
US7180404B2 (en) * 2004-03-17 2007-02-20 Battelle Energy Alliance, Llc Wireless sensor systems and methods, and methods of monitoring structures
US20070228874A1 (en) * 2004-09-13 2007-10-04 Denso Corporation Piezoelectric actuator
US7325456B2 (en) * 2003-09-22 2008-02-05 Hyeung-Yun Kim Interrogation network patches for active monitoring of structural health conditions
US7377179B2 (en) * 2005-11-14 2008-05-27 General Electric Company System, method, and apparatus for wireless non-powered stress history and fatigue monitoring of a structure
US20080203851A1 (en) * 2007-02-27 2008-08-28 Iptrade, Inc. Piezoelectric package with porous conductive layers
US7429813B2 (en) * 2004-01-15 2008-09-30 Robert Bosch Gmbh Piezoelectric actuator
US7536912B2 (en) * 2003-09-22 2009-05-26 Hyeung-Yun Kim Flexible diagnostic patches for structural health monitoring
US7656076B1 (en) * 2008-07-15 2010-02-02 Iptrade, Inc. Unimorph/bimorph piezoelectric package
US7729035B2 (en) * 2003-09-22 2010-06-01 Hyeung-Yun Kim Acousto-optic modulators for modulating light signals

Patent Citations (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4480480A (en) * 1981-05-18 1984-11-06 Scott Science & Technology, Inc. System for assessing the integrity of structural systems
US4849668A (en) * 1987-05-19 1989-07-18 Massachusetts Institute Of Technology Embedded piezoelectric structure and control
US5421204A (en) * 1993-06-08 1995-06-06 Svaty, Jr.; Karl J. Structural monitoring system
US5507188A (en) * 1993-06-08 1996-04-16 Svaty, Jr.; Karl J. Structural monitoring system
US5520055A (en) * 1993-11-13 1996-05-28 Dornier Gmbh Apparatus for monitoring the fatigue strength of structures
US6781285B1 (en) * 1994-01-27 2004-08-24 Cymer, Inc. Packaged strain actuator
US6069433A (en) * 1994-01-27 2000-05-30 Active Control Experts, Inc. Packaged strain actuator
US6076405A (en) * 1994-08-31 2000-06-20 Honeywell International Inc. Remote self-powered structure monitor
US6240783B1 (en) * 1998-05-02 2001-06-05 Usbi, Co Bridge monitoring system
US6928881B2 (en) * 2000-06-29 2005-08-16 University College London Method and apparatus for monitoring structural fatigue and use
US7065846B2 (en) * 2002-07-11 2006-06-27 Ceramtec Ag Innovative Ceramic Engineering Insulation for piezoceramic multilayer actuators
US20040078170A1 (en) * 2002-10-17 2004-04-22 Don Di Marzio System and method for monitoring a structure
US7325605B2 (en) * 2003-04-08 2008-02-05 Halliburton Energy Services, Inc. Flexible piezoelectric for downhole sensing, actuation and health monitoring
US7234519B2 (en) * 2003-04-08 2007-06-26 Halliburton Energy Services, Inc. Flexible piezoelectric for downhole sensing, actuation and health monitoring
US20040200613A1 (en) * 2003-04-08 2004-10-14 Fripp Michael L. Flexible piezoelectric for downhole sensing, actuation and health monitoring
US7117742B2 (en) * 2003-09-22 2006-10-10 Advanced Structure Monitoring, Inc. Sensors and systems for structural health monitoring
US20060260402A1 (en) * 2003-09-22 2006-11-23 Advanced Structure Monitoring, Inc. Sensors for monitoring structural health conditions
US7197931B2 (en) * 2003-09-22 2007-04-03 Hyeung-Yun Kim Sensors for monitoring structural health conditions
US7729035B2 (en) * 2003-09-22 2010-06-01 Hyeung-Yun Kim Acousto-optic modulators for modulating light signals
US7286964B2 (en) * 2003-09-22 2007-10-23 Advanced Structure Monitoring, Inc. Methods for monitoring structural health conditions
US20050061076A1 (en) * 2003-09-22 2005-03-24 Hyeung-Yun Kim Sensors and systems for structural health monitoring
US7325456B2 (en) * 2003-09-22 2008-02-05 Hyeung-Yun Kim Interrogation network patches for active monitoring of structural health conditions
US7596470B2 (en) * 2003-09-22 2009-09-29 Advanced Structure Monitoring, Inc. Systems and methods of prognosticating damage for structural health monitoring
US7590510B2 (en) * 2003-09-22 2009-09-15 Advanced Structure Monitoring, Inc. Systems and methods for identifying damage in a structure
US7536912B2 (en) * 2003-09-22 2009-05-26 Hyeung-Yun Kim Flexible diagnostic patches for structural health monitoring
US7429813B2 (en) * 2004-01-15 2008-09-30 Robert Bosch Gmbh Piezoelectric actuator
US7180404B2 (en) * 2004-03-17 2007-02-20 Battelle Energy Alliance, Llc Wireless sensor systems and methods, and methods of monitoring structures
US20070228874A1 (en) * 2004-09-13 2007-10-04 Denso Corporation Piezoelectric actuator
US7377179B2 (en) * 2005-11-14 2008-05-27 General Electric Company System, method, and apparatus for wireless non-powered stress history and fatigue monitoring of a structure
US20080218026A1 (en) * 2007-02-27 2008-09-11 Iptrade, Inc. Piezoelectric package with enlarged conductive layers
US20080203851A1 (en) * 2007-02-27 2008-08-28 Iptrade, Inc. Piezoelectric package with porous conductive layers
US7656076B1 (en) * 2008-07-15 2010-02-02 Iptrade, Inc. Unimorph/bimorph piezoelectric package

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110116940A1 (en) * 2009-11-17 2011-05-19 Cameron International Corporation Viscoelastic compressor pulsation dampener
US8863784B2 (en) 2010-04-22 2014-10-21 Cameron International Corporation Viscoelastic damped jumpers
US9500247B2 (en) 2010-11-01 2016-11-22 University Of Houston Pounding tune mass damper with viscoelastic material
CN102062747A (en) * 2010-11-15 2011-05-18 湖南大学 Method for monitoring peeling of steel tube wall of concrete filled steel tube member based on piezoelectric ceramics and wavelet packet analysis
CN102322986A (en) * 2011-08-08 2012-01-18 大连理工大学 Embedded concrete dynamic damage overall-process pressure sensor
CN102384802A (en) * 2011-08-08 2012-03-21 大连理工大学 Embedded type sensor of overall process shear stress of concrete dynamic damage
CN104285131A (en) * 2012-05-25 2015-01-14 意法半导体股份有限公司 A package, made of building material, for a parameter monitoring device, within a solid structure, and relative device
US9791303B2 (en) 2012-05-25 2017-10-17 Stmicroelectronics S.R.L. Package, made of building material, for a parameter monitoring device, within a solid structure, and relative device
CN103048384A (en) * 2012-12-20 2013-04-17 刘铁军 Method for monitoring concrete humidity based on piezoelectric smart aggregate
CN103335752A (en) * 2013-06-20 2013-10-02 中山市拓维电子科技有限公司 Remotely and dynamically surveying system and method for road pre-buried shear stress
DE102013112267A1 (en) * 2013-11-07 2015-05-07 Heraeus Deutschland GmbH & Co. KG Semiconductor module with a semiconductor device covering a cover mass
CN103792031A (en) * 2014-02-26 2014-05-14 长沙理工大学 FRP rib interface shearing strength monitoring device and method based on length deformation type PZT
CN103837886A (en) * 2014-03-27 2014-06-04 江苏三川智能科技有限公司 Earthquake and rockburst locating method based on piezoelectric intelligent aggregates
CN106770653A (en) * 2016-12-05 2017-05-31 大连理工大学 It is a kind of to stack formula piezoelectric intelligent aggregate for concrete structure health monitoring
CN107275474A (en) * 2017-05-04 2017-10-20 浙江大学 A kind of piezoelectricity girder test specimen and preparation method thereof and test method
CN106948488A (en) * 2017-05-05 2017-07-14 长沙理工大学 Preparation method, combination beam and the monitoring device of compound transfer structure for SRC beams
CN107146844A (en) * 2017-05-19 2017-09-08 浙江大学 The preparation method and experimental method of a kind of road piezoelectric energy-capturing device
CN107644121A (en) * 2017-08-18 2018-01-30 昆明理工大学 The reverse three-dimensionalreconstruction and body modeling method of a kind of ground surface material skeleton structure
CN107632069A (en) * 2017-09-29 2018-01-26 长安大学 A kind of concrete beam strengthening steel sheet peeling off detecting system and detection method
CN108818882A (en) * 2018-03-06 2018-11-16 华侨大学 A kind of concrete intelligent aggregate and preparation method thereof
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